1. Fischer trapezoidal profiles as roof covering
The minimum roof pitch of roof coverings made of trapezoidal profiles should not be less than 3° without cross joints and roof openings and 5° with cross joints and roof openings.
In Part 3 of DIN 18807, point 4.9.3 'Precipitation' states in very general terms how the penetration of water in roof and wall systems can be permanently prevented by suitable measures. This also mentions 'the implementation of additional sealing measures in the area of connections, transitions and openings (e.g. at windows, doors, lighting and ventilation equipment, etc.) as well as at the transverse and longitudinal joints of the trapezoidal profiles as roofing'.
With regard to the waterproofing of roof coverings made of trapezoidal profiles, there are detailed specifications as recognized rules of building technology, e.g. the 'IFBS guideline for the installation of profiled steel sheets for roof, wall and ceiling constructions' as an appendix to 'Instructions for coverings and claddings with profiled sheet metal panels and strips and industrially prefabricated elements'. Furthermore the 'IFBS guideline for the planning and execution of double-skin, thermally insulated, non-ventilated metal roofs'.
The IFBS installation guideline states under 8.2.5, Longitudinal joint sealing: 'Continuous sealing must be provided for roof pitches < 8°' and the IFBS guideline for the planning and execution of double-shell, thermally insulated, non-ventilated metal roofs states on page 22: 'Longitudinal joint sealing recommended for roof pitches < 5° continuous sealing'.
In the 'Instructions for roof coverings with profiled metal sheets and strips', see.8.2 Overlaps and roof pitches: For roof pitches of 8° and below, additional continuous seals are required within the side and height overlaps'.